CN110394537B

CN110394537B - Friction stir welding method

Info

Publication number: CN110394537B
Application number: CN201910328162.0A
Authority: CN
Inventors: 山口修平; 德田善范; 糟谷成孝; 寺泽槙惠; 本田守
Original assignee: Aisin Seiki Co Ltd
Current assignee: Aisin Corp
Priority date: 2018-04-24
Filing date: 2019-04-23
Publication date: 2021-06-15
Anticipated expiration: 2039-04-23
Also published as: JP7102900B2; CN110394537A; JP2019188433A

Abstract

Provided is a friction stir welding method capable of suppressing the occurrence of a welding defect. The friction stir welding method includes the steps of scanning a friction stir welding tool FT along a first friction stir welding target site having a planar outer peripheral surface extending in a predetermined direction and a second friction stir welding target site having a curved outer peripheral surface extending in the predetermined direction from an end of the first friction stir welding target site in an extending direction of the outer peripheral surface, and successively and sequentially welding the first friction stir welding target site and the second friction stir welding target site. The relative position or posture of the friction stir welding tool and the members to be welded is controlled so that the rear half of the shoulder of the friction stir welding tool in the scanning direction enters deeper into the friction stir welding target site than the front half, and the depth of entry of the shoulder into the first friction stir welding target site is the same as the depth of entry of the shoulder into the second friction stir welding target site.

Description

Friction stir welding method

Technical Field

The present invention relates to a friction stir welding method.

Background

For example, as described in patent document 1 below, a friction stir welding method of 2 metal members is known. In the first step (butt joint step) of the friction stir welding method, first, end faces of 2 metal members (first member and second member) as members to be welded are butted. The first member and the second member are disposed so that no step is formed at a boundary portion between the first member and the second member. In the second step (bonding step), the tip portion (probe portion) of the friction stir tool is pushed into the friction stir bonding target portion and scanned along the friction stir bonding target portion. Thereby, the friction stir welding target portions (i.e., portions located on both sides of the butted end surfaces) are stirred and plastically fluidized. Thus joining the first and second components.

Patent document 1: japanese patent laid-open publication No. 2016-74014

Generally, when the friction stir welding tool scans along a friction stir welding target portion, the center axis of the friction stir welding tool is not perpendicular to the surface of the welding target portion, but is slightly inclined with respect to the surface (or normal line). That is, the distal end side (probe side) of the friction stir tool is located forward in the scanning direction than the proximal end side (shank side). The angle of inclination of the central axis with respect to the normal is called the advance angle. The advance angle is set to 3 °, for example. As described above, by disposing the friction stir tool obliquely with respect to the normal line, the rear half portion side in the scanning direction of the shoulder portion (the tip end of the shank portion) of the friction stir tool is deeper into the portion to be welded than the front half portion side. Therefore, the metal material that is plastically fluidized on the rear side in the scanning direction by being stirred by the friction stir tool is suppressed from floating (bulging of the surface), and the occurrence of a bonding defect (void) can be suppressed.

Here, as shown in fig. 22, a process of joining the first friction stir welding target portion WP1 and then joining the second friction stir welding target portion WP2 of the butted first member P1 and second member P2 is considered. The outer peripheral surface S1 of the first friction stir welding target portion WP1 is planar, and the outer peripheral surface S2 of the second friction stir welding target portion WP2 is an arc surface continuous along the outer peripheral surface S1.

First, the friction stir tool FT is press-fitted into the first friction stir welding target portion WP1. Then, the friction stir tool FT is moved in parallel toward the second friction stir welding target portion WP2 side (rightward in fig. 23). In the joining step of the first friction stir welding target portion WP1, the advance angle θ is set to a predetermined value (e.g., 3 °). In other words, the depth d of the rear half of the shoulder portion into the first friction stir welding target portion WP1 is set to an optimum value d that can suppress the floating of the metal material that plastically flows₀(e.g., 0.3 mm). The tip (probe portion) of the friction stir tool FT is substantially a truncated cone, but in the following description, the tip DP of the probe portion PR is pointed. In addition, in FIG. 23, dottedLine La represents the optimum value d of the penetration depth d from the outer peripheral surfaces S1, S2₀The position of (a). The dotted line Lb indicates the optimum value D of the stirring depth D as the distance from the outer peripheral surfaces S1 and S2₀The position of (a).

As shown in fig. 23, when the tip DP of the probe portion PR reaches the boundary BD between the first and second friction stir welding target portions WP1 and WP2₁₂At this time, the friction stir tool FT starts rotating around the center axis O of the outer peripheral surface S2. Here, only the rotation angle α of the friction stir tool FT around the center axis O increases, and other parameters such as the advance angle θ (the angle of the center axis CA with respect to the normal N of each point of the outer peripheral surface S2) and the position of the friction stir tool FT in the extending direction of the center axis CA are not changed. In this case, the stirring depth D (the distance from the outer peripheral surfaces S1, S2 to the tip DP of the probe portion PR) is maintained at the optimum value D₀. However, as shown in fig. 23, when the friction stir tool FT starts rotating about the center axis O, the depth d of penetration of the shoulder portion (the tip of the shank SH) into the portion to be friction stir welded WP (the first portion to be friction stir welded WP1 or the second portion to be friction stir welded WP2) becomes smaller than the optimum value d₀Is small. Therefore, as shown in fig. 24, the metal material that has been plastically fluidized may float up, and the outer peripheral surface S2 may bulge out, thereby causing a bonding defect (void) to occur inside the second friction stir bonding target portion WP2. In fig. 24, the locus of the rear end of the shoulder portion of the friction stir tool FT is indicated by a two-dot chain line.

Disclosure of Invention

The present invention has been made to solve the above-described problems, and an object thereof is to provide a friction stir welding method capable of suppressing occurrence of a welding defect. In the following description of the respective constituent elements of the present invention, the corresponding portions of the embodiments are denoted by reference numerals for easy understanding of the present invention, but the respective constituent elements of the present invention should not be construed as being limited to the configurations of the reference numerals of the embodiments.

In order to achieve the above object, a friction stir welding method according to the present invention is a friction stir welding method for continuously welding a first friction stir welding target portion WP1 and a second friction stir welding target portion WP2 formed by portions positioned on both sides of a butting face of 2

members

10 and 20 in this order, and controlling relative positions or postures of the friction stir welding tool and the 2 members by scanning a friction stir welding tool FT along the first friction stir welding target portion having a planar outer peripheral surface S1 extending in a predetermined direction and the second friction stir welding target portion having a curved outer peripheral surface S2 extending in the predetermined direction from an end of the outer peripheral surface of the first friction stir welding target portion in the extending direction, so that a rear half of a shoulder portion of the friction stir welding tool in the scanning direction enters deeper into the friction stir welding target site than a front half thereof, and an entering depth d of the shoulder portion into the first friction stir welding target site is the same as an entering depth d of the shoulder portion into the second friction stir welding target site.

In this case, the first friction stir welding target site may be set such that the advance angle θ of the friction stir tool is set to a predetermined value, and when the tip end portion DP of the friction stir tool reaches the boundary BD between the first friction stir welding target site and the second friction stir welding target site₁₂Then, the friction stir tool is rotated around the center axis O of the outer peripheral surface S2 of the second friction stir welding target portion, and the advance angle is gradually changed.

In this case, when the portion of the shoulder portion on the rear end side in the scanning direction reaches the boundary portion between the first friction stir welding target portion and the second friction stir welding target portion, the friction stir tool may be started to rotate around the central axis of the outer peripheral surface of the second friction stir welding target portion.

In this case, the advance angle of the friction stir welding tool at the first friction stir welding target site may be set to a predetermined value, and when the tip end portion of the friction stir welding tool reaches the boundary portion between the first friction stir welding target site and the second friction stir welding target site, the friction stir welding tool may be rotated around the central axis of the outer peripheral surface of the second friction stir welding target site to gradually change the stir depth D of the friction stir welding tool. Further, the "stirring depth" of the present invention corresponds to the distance from the outer peripheral surfaces of the 2 members to be joined to the tip end of the friction stirring tool.

According to the present invention, the depth of penetration of the shoulder portion of the friction stir welding tool can be maintained at an optimum value from the first friction stir welding target site having the planar outer peripheral surface to the second friction stir welding target site having the curved outer peripheral surface over the entire surface. Therefore, the occurrence of the bonding defect as shown in fig. 24 can be suppressed.

Drawings

Fig. 1 is a perspective view of a first member and a second member joined using the friction stir welding method of the first to third embodiments of the present invention.

Fig. 2 is a schematic perspective view showing a bonding step in the friction stir bonding method according to the present invention.

Fig. 3 is a cross-sectional view showing a case where a friction stir tool scans along a first friction stir welding target portion at an interface between a first member and a second member according to the first to third embodiments of the present invention.

Fig. 4 is a cross-sectional view showing a state where the friction stir tool reaches a boundary portion between the first friction stir welding target site and the second friction stir welding target site.

Fig. 5 is a cross-sectional view showing the posture of the friction stir welding tool in a case where the friction stir welding tool is slightly rotated along the second friction stir welding target portion without changing the advancing angle.

Fig. 6 is a cross-sectional view showing a case where the friction stir tool is rotated along the second friction stir welding target portion while gradually increasing the advance angle.

Fig. 7 is a cross-sectional view showing a state where the rear end of the shoulder portion in the scanning direction reaches the boundary portion between the first friction stir welding target site and the second friction stir welding target site.

Fig. 8 is a cross-sectional view showing a case where the friction stir tool is rotated along the second friction stir welding target portion without changing the advance angle.

Fig. 9 is a cross-sectional view showing a state where the tip of the probe portion reaches a boundary portion between the first friction stir welding target site and the second friction stir welding target site.

Fig. 10 is a cross-sectional view showing the posture of the friction stir welding tool in a case where the friction stir welding tool is moved slightly in parallel along the third friction stir welding target portion without changing the advancing angle.

Fig. 11 is a cross-sectional view showing a case where the advance angle is gradually increased and the friction stir tool is moved in parallel along the third friction stir welding target portion.

Fig. 12 is a cross-sectional view showing a state in which the rear end of the shoulder portion in the scanning direction reaches the boundary portion between the second friction stir welding target site and the third friction stir welding target site.

Fig. 13 is a cross-sectional view showing a case where the friction stir tool is moved in parallel along the third friction stir welding target site.

Fig. 14 is a cross-sectional view showing a state in which the rear end of the shoulder portion in the scanning direction reaches the boundary portion between the first friction stir welding target portion and the second friction stir welding target portion according to the second embodiment of the present invention.

Fig. 15 is a cross-sectional view showing a case where the friction stir tool is rotated along the second friction stir welding target portion.

Fig. 16 is a cross-sectional view showing the posture of the friction stir welding tool in the case where the friction stir welding tool is slightly rotated along the second friction stir welding target site without changing the pushing amount of the friction stir welding tool according to the third embodiment of the present invention.

Fig. 17 is a cross-sectional view showing a case where the friction stir tool is rotated along the second friction stir welding target portion while the push-in amount is gradually increased.

Fig. 18 is a cross-sectional view showing a case where the friction stir tool is rotated along the second friction stir welding target portion without changing the push-in amount.

Fig. 19 is a cross-sectional view showing the posture of the friction stir welding tool in a case where the friction stir welding tool is moved in parallel along the third friction stir welding target portion without changing the push-in amount.

Fig. 20 is a cross-sectional view showing a state where the rear end of the shoulder portion in the scanning direction reaches the boundary portion between the second friction stir welding target site and the third friction stir welding target site.

Fig. 21 is a cross-sectional view showing a case where the friction stir tool is moved in parallel along the third friction stir welding target portion without changing the push-in amount.

Fig. 22 is a schematic perspective view showing a bonding step in a conventional friction stir bonding method.

Fig. 23 is a cross-sectional view showing a case where a friction stir tool scans along a first friction stir welding target site and a second friction stir welding target site on an abutting surface between a first member and a second member according to a conventional friction stir welding method.

Fig. 24 is a sectional view showing a defective joint.

Detailed Description

(first embodiment)

The following describes a procedure (butt joint step and joining step) of joining the first member 10 and the second member 20 shown in fig. 1 to produce a box-shaped (shell-shaped) product that is open in one direction, by using the friction stir welding method according to the first embodiment of the present invention. The first member 10 and the second member 20 are made of aluminum alloy. The first member 10 has a side wall 11 and a peripheral wall 12. The side wall portion 11 is a substantially rectangular plate-like portion. That is, the side wall portion 11 has opposing

long side portions

111 and 113 and

short side portions

112 and 114. The intersection (corner C1a) of the long side portion 111 and the short side portion 112 of the side wall portion 11 is curved in an arc shape. In addition, the intersection (corner C1b) of the long side portion 113 and the short side portion 112 of the side wall portion 11 is curved in an arc shape.

The peripheral wall portion 12 extends from the peripheral edge portion of the side wall portion 11 perpendicularly to the surface of the side wall portion 11, and is arranged to extend along the peripheral edge portion of the side wall portion 11. The peripheral wall portion 12 is formed along the peripheral edge portion of the side wall portion 11 except for the short side portion 114. Specifically, the peripheral wall portion 12 includes a first wall portion 121 along the long side 111, a second wall portion 122 along the corner portion C1a, a third wall portion 123 along the short side 112, a fourth wall portion 124 along the corner portion C1b, and a fifth wall portion 125 along the long side 113. The outer peripheral surfaces of the first wall portion 121, the third wall portion 123, and the fifth wall portion 125 are flat surfaces. The outer peripheral surfaces of the second wall portion 122 and the fourth wall portion 124 are arc surfaces. Further, the widths (the dimension in the direction parallel to the thickness direction of the side wall portion 11) of the first wall portion 121 to the fifth wall portion 125 are equal. In addition, the wall thicknesses of the first wall portion 121 to the fifth wall portion 125 are equal. The end surfaces E1 on the opposite side of the side wall portion 11, which are the end surfaces in the width direction of the first to fifth wall portions 121 to 125, are parallel to the surface of the side wall portion 11.

The second member 20 has a shape that is plane-symmetrical with respect to the end face of the peripheral wall portion 12 of the first member 10. That is, the second member 20 has a side wall portion 21 similar to the side wall portion 11 and a peripheral wall portion 22 similar to the peripheral wall portion 12. The side wall portion 21 has

long side portions

211 and 213 and

short side portions

212 and 214. The intersection (corner C2a) of the long side portion 211 and the short side portion 212 of the side wall portion 21 is curved in an arc shape. In addition, the intersection (corner C2b) of the long side portion 213 and the short side portion 212 of the side wall portion 21 is curved in an arc shape. The peripheral wall portion 22 has first to fifth wall portions 221 to 225 similar to the first to fifth wall portions 121 to 125. The end surfaces of the first to fifth wall portions 221 to 225 in the width direction, that is, the end surface E2 on the opposite side to the side wall portion 21 are parallel to the surface of the side wall portion 21.

As described below, the peripheral wall portion 12 of the first member 10 and the peripheral wall portion 22 of the second member 20 are butted against each other, and the friction stir tool FT scans along the friction stir welding target portions WP formed at the portions located on both sides of the butted surface, thereby welding the first member 10 and the second member 20 (see fig. 2). The friction stir tool FT is attached to the drive device DR. The drive device DR includes a control device and various actuators, which are not shown. The control device controls various parameters regarding the position and orientation of the friction stir tool FT and the rotation speed around the center axis CA in accordance with a predetermined computer program. The various actuators are operated in accordance with the parameters, and the rotational speed, position, and posture of the friction stir tool FT are changed.

(Butt-joining step)

Next, the docking process will be described. The end face E1 of the peripheral wall portion 12 of the first member 10 and the end face E2 of the peripheral wall portion 22 of the second member 20 are butted. The first member 10 and the second member 20 are disposed so that no step is formed at the boundary between the peripheral wall 12 and the peripheral wall 22. That is, the two members are disposed so that the outer peripheral surface of the peripheral wall portion 12 of the first member 10 and the outer peripheral surface of the peripheral wall portion 22 of the second member 20 are continuous. In the following description, a portion where first wall portion 121 and first wall portion 221 are joined, among friction stir welding target portions WP of first member 10 and second member 20, is referred to as a first friction stir welding target portion WP1. A portion where the second wall portion 122 and the second wall portion 222 are joined is referred to as a second friction stir welding target portion WP2. A portion where the third wall portion 123 and the third wall portion 223 are joined is referred to as a third friction stir welding target portion WP3. A portion where the fourth wall portion 124 and the fourth wall portion 224 are joined is referred to as a fourth friction stir welding target portion WP4. A portion where the fifth wall portion 125 and the fifth wall portion 225 are joined is referred to as a fifth friction stir welding target portion WP5.

The first member 10 and the second member 20 which are butted as described above are fixed by being attached to a not-shown support device. In the following description, the extending direction of the outer peripheral surface S1 of the first friction stir welding target portion WP1 is referred to as the front-rear direction, and the arrangement direction of the first member 10 and the second member 20 is referred to as the left-right direction. The normal direction of the outer peripheral surface S1 of the first friction stir welding target portion WP1 is referred to as the vertical direction.

(joining Process)

Next, the bonding step is explained. In this step, the welding is performed in the order of the welding of the first friction stir welding target portion WP1, the welding of the second friction stir welding target portion WP2, and the welding of the third friction stir welding target portion WP3. Then, the fourth welding target portion WP4 and the fifth welding target portion continue to be sequentially performedJoining of WP5. The above-described steps are continuously performed. The series of steps from the joining of the first friction stir welding target portion WP1 to the joining of the third welding target portion WP3 is substantially the same as the series of steps from the joining of the third welding target portion WP3 to the joining of the fifth welding target portion WP5. In view of this, a series of steps from the joining of the first friction stir welding target portion WP1 to the joining of the third welding target portion WP3 will be described below, and a series of steps from the joining of the third welding target portion WP3 to the joining of the fifth welding target portion WP5 will be omitted from the description. In fig. 3 to 20, the tip (probe portion PR) of the friction stir tool FT is substantially a truncated cone, but hereinafter, the tip DP of the probe portion PR will be described as a sharp shape. The broken line La indicates the optimum value d of the distance from the outer peripheral surfaces S1, S2, and S3 to the depth d₀The position of (a). The broken line Lb indicates the optimum value D of the distance from the outer peripheral surface S1, S2, S3 to the stirring depth D₀The position of (a).

First, as shown in fig. 2, the friction stir tool FT is disposed above the first member 10 and the second member 20. Next, the positions of the first member 10, the second member 20, and the friction stir tool FT in the left-right direction are set so that the position of the center axis CA of the friction stir tool FT in the left-right direction matches the position of the abutting surface (i.e., the end surface E1 and the end surface E2) of the first member 10 and the second member 20 in the left-right direction. The position of the friction stir welding tool FT is set so that the distal end portion of the friction stir welding tool FT is located above the end portion of the first friction stir welding target site WP1 in the front-rear direction, that is, the end portion on the opposite side of the second friction stir welding target site WP2.

Next, the friction stir tool FT descends while rotating around the center axis CA, and the tip end portion of the friction stir tool FT is press-fitted into the boundary portion between the first wall portion 121 and the first wall portion 221. As shown in fig. 3, the advance angle θ is set to, for example, 3 °. Thereby, the rear half portion of the shoulder portion of the friction stir tool FT (the rear side portion of the friction stir tool FT in the scanning direction) is more advanced than the front half portion (the front side portion of the friction stir tool FT in the scanning direction)And deeply enters the first friction stir welding target portion WP1. Specifically, the depth d of penetration of the shoulder portion into the first friction stir welding target portion WP1 is set to an optimum value d that can suppress the floating of the metal material that flows plastically₀(e.g., 0.3 mm). The tip of the shoulder is located slightly above the outer peripheral surface S1.

Next, the friction stir tool FT scans forward (rightward in fig. 3) (parallel movement). Among the parameters relating to the position and orientation of the friction stir tool FT, the parameters are not changed except for the parameter relating to the position in the front-rear direction. Thereby, the tip DP of the probe portion PR moves along the broken line Lb. That is, the stirring depth D is maintained at the optimum value D₀. Further, the rear end RP of the shoulder in the scanning direction (i.e., the deepest portion of the shoulder in the friction stir welding target portion WP) moves along a broken line (first line) La in fig. 3. That is, the depth of entry d is maintained at an optimum value d₀. As shown in fig. 4, when the tip DP of the probe portion PR of the friction stir tool FT reaches the boundary BD between the first friction stir welding target portion WP1 and the second friction stir welding target portion WP2₁₂At this time, the forward scanning of the friction stir tool FT is stopped.

Next, the friction stir tool FT starts scanning (rotating) around the center axis O of the outer peripheral surface S2 of the second friction stir welding target portion WP2. At this time, various parameters regarding the position and the posture of the friction stir tool FT are changed such that the tip DP of the probe portion PR of the friction stir tool FT moves along a broken line (second line) Lb in fig. 4, and the rear end RP of the shoulder in the scanning direction moves along a broken line La in fig. 4. That is, various parameters are changed so that the stirring depth D (the distance from the outer peripheral surface S2 to the tip DP of the probe portion PR) is maintained at the optimum value D₀And the depth d of penetration of the shoulder of the friction stir tool FT is maintained at an optimum value d₀(e.g., 0.3 mm).

From the state of fig. 4, the tip DP of the probe portion PR moves along the broken line Lb in fig. 5 by increasing the rotation angle α of the friction stir tool FT about the center axis O. That is, the stirring depth D is maintained at the optimum value D₀. Here, it is assumed that, as shown in FIG. 5, stirring is performed by frictionWhen the rotation angle α of the tool FT about the center axis O starts to increase, if any of the parameters relating to the position and orientation of the friction stir tool FT other than the rotation angle α is not changed, the rear end RP of the shoulder in the scanning direction deviates from the broken line La in fig. 5. That is, the entry depth d becomes gradually smaller. As shown in fig. 6, the friction stir tool FT is gradually rotated around the tip DP of the probe portion PR to increase the advancing angle θ so that the rotating angle α of the friction stir tool FT gradually increases and the depth of penetration d is maintained at the optimum value d₀. When the rear end RP of the shoulder in the scanning direction reaches the boundary BD₁₂In this case (see fig. 7), the rotation of the friction stir tool FT about the tip DP (change of the advance angle θ) is stopped.

Subsequently, as shown in fig. 8, the friction stir tool FT further rotates around the center axis O. Of the parameters of the position and orientation of the friction stir tool FT, the parameters are not changed except for the rotation angle α. That is, the advance angle θ at the time shown in fig. 7 is maintained. Thereby, the rear end RP of the shoulder in the scanning direction moves along the broken line La in fig. 8 and 9. That is, the depth of entry d is maintained at an optimum value d₀. In fig. 8 and 9, the tip DP of the probe portion PR moves along a broken line Lb. That is, the stirring depth D is maintained at the optimum value D₀. When the rotation angle α reaches "90 °" (i.e., the tip DP of the probe portion PR reaches the boundary portion BD)₂₃In this case (see fig. 9)), the rotation of the friction stir tool FT about the center axis O is stopped.

Subsequently, the friction stir tool FT starts scanning downward (parallel movement). Thereby, the tip DP of the probe portion PR moves along the broken line Lb in fig. 11 and 12. That is, the stirring depth D is maintained at the optimum value D₀. Here, as shown in fig. 10, when the friction stir tool FT starts scanning downward, if, of the parameters relating to the position and orientation of the friction stir tool FT, the parameters other than the parameters relating to the position in the vertical direction are not changed, the rear end RP of the shoulder in the scanning direction deviates from the broken line La in fig. 10. That is, the entry depth d gradually becomes larger. As shown in FIG. 11, the friction stir tool FT is rotated gradually around the tip DP of the probe portion PR until it is reducedAn advance angle theta for keeping the depth d of the friction stir tool FT at an optimum value d while moving the friction stir tool FT in parallel downward₀. When the rear end RP of the shoulder in the scanning direction reaches the boundary BD₂₃In this case (see fig. 12), the rotation of the friction stir tool FT about the tip DP (change of the advance angle θ) is stopped.

Next, as shown in fig. 13, the friction stir tool FT is further scanned downward (moved in parallel). In addition, of the parameters regarding the position and orientation of the friction stir tool FT, parameters other than the parameters regarding the position in the vertical direction are not changed. Thereby, the tip DP of the probe portion PR moves along the broken line Lb in fig. 13. That is, the stirring depth D is maintained at the optimum value D₀. In addition, the rear end RP of the shoulder in the scanning direction moves along the broken line La in fig. 13. That is, the depth of entry d is maintained at an optimum value d₀. As described above, the first to third portions to be friction stir welded WP1 to WP3 are welded.

As described above, in the present embodiment, the position of the friction stir tool FT in the front-rear direction, the position of the friction stir tool FT in the vertical direction, and the rotation angle α are controlled so that the distal end DP of the probe portion PR moves along the broken line Lb. Also, the advance angle θ is appropriately changed so that the rear end RP of the shoulder in the scanning direction moves along the broken line La. That is, according to the present embodiment, the stirring depth D is maintained at the optimum value D₀So as to make the bonding strength of each part uniform and maintain the depth d at the optimum value d₀Thereby, occurrence of a bonding defect can be suppressed.

(second embodiment)

Next, a procedure for manufacturing a product similar to that of the first embodiment by using the friction stir welding method according to the second embodiment of the present invention will be described.

(Butt-joining step)

In the present embodiment, the first member 10 and the second member 20 are butted against each other as in the first embodiment. Since the specific procedure of this docking process is the same as that of the first embodiment, the description thereof will be omitted.

(joining Process)

Similarly to the first embodiment, the first to fifth portions to be friction stir welded WP1 to WP5 are continuously welded in this order. A series of steps from the joining of the first friction stir welding target portion WP1 to the joining of the third friction stir welding target portion WP3 is substantially the same as a series of steps from the joining of the third friction stir welding target portion WP3 to the joining of the fifth friction stir welding target portion WP5. Therefore, a series of steps from the joining of the first friction stir welding target portion WP1 to the joining of the third friction stir welding target portion WP3 will be described below, and a series of steps from the joining of the third friction stir welding target portion WP3 to the joining of the fifth friction stir welding target portion WP5 will be omitted from the description.

First, the position and posture of the friction stir tool FT with respect to the first member 10 and the second member 20 are set in the same manner as in the start of the joining according to the first embodiment.

Next, as in the first embodiment, the friction stir tool FT descends while rotating about the center axis CA, and the tip end portion of the friction stir tool FT is pushed into the rear end portion of the first friction stir welding target site WP1 (see fig. 3). The advance angle θ is set to 3 °, for example. Thus, the depth d of penetration of the shoulder portion into the first friction stir welding target portion WP1 is set to the optimum value d₀(e.g., 0.3 mm).

Next, the friction stir tool FT scans (moves in parallel) forward (rightward in fig. 3). Among the parameters relating to the position and orientation of the friction stir tool FT, parameters other than the parameter relating to the position in the front-rear direction are not changed. Thereby, the rear end RP of the shoulder in the scanning direction moves along the broken line La in fig. 3. That is, the depth of entry d is maintained at an optimum value d₀. Further, the tip DP of the probe portion PR moves along the broken line Lb. That is, the stirring depth D is maintained at the optimum value D₀。

In the second embodiment, unlike the first embodiment, the tip DP of the probe portion PR of the friction stir tool FT reaches the boundary portion BD even when the tip DP of the probe portion PR reaches the boundary portion BD₁₂' MoThe forward movement of the wiping/stirring tool FT is not stopped. In the second embodiment, as shown in fig. 14, when the rear end RP of the shoulder portion of the friction stir tool FT in the scanning direction reaches the boundary BD between the first friction stir welding target portion WP1 and the second friction stir welding target portion WP2₁₂At this time, the forward movement of the friction stir tool FT is stopped. Thus, as shown in fig. 14, the tip DP of the probe portion PR passes through the boundary portion BD₁₂And moves forward while deviating from the broken line Lb. That is, when the tip DP of the probe PR passes through the boundary BD₁₂The stirring depth D becomes more than the optimum value D₀Shallow.

Next, as shown in fig. 15, the friction stir tool FT scans (rotates) around the center axis O of the outer peripheral surface S2. Among the parameters relating to the position and orientation of the friction stir tool FT, parameters other than the rotation angle α around the central axis O are not changed. Thereby, the rear end RP of the shoulder in the scanning direction moves along the broken line La in fig. 15. That is, the depth of entry d is maintained at an optimum value d₀. On the other hand, the tip DP of the probe portion PR moves away from the broken line Lb in fig. 15. I.e. the mixing depth D is less than the optimum value D₀Shallow. When the rotational angle α of the friction stir tool FT about the center axis O reaches "90 °", the rear end RP of the shoulder in the scanning direction reaches the boundary BD between the second friction stir welding target portion WP2 and the third friction stir welding target portion WP3₂₃. The tip DP of the probe portion PR exceeds the boundary BD₂₃After entering into the third portion to be friction stir welded WP3, the portion intersects the broken line Lb. At this time, the rotation of the friction stir tool FT about the center axis O is stopped.

Subsequently, the friction stir tool FT scans downward (moves in parallel). Among the parameters relating to the position and orientation of the friction stir tool FT, parameters other than the parameters relating to the position in the vertical direction are not changed. Thereby, the rear end RP of the shoulder in the scanning direction moves along the broken line La in fig. 15. That is, the depth of entry d is maintained at an optimum value d₀. In fig. 15, the tip DP of the probe portion PR moves along a broken line Lb. That is, the stirring depth D is maintained at the optimum value D₀. In doing so as described above, it is possible to,the first to third portions to be friction stir welded WP1 to WP3 are welded.

As described above, in the present embodiment, the position of the friction stir tool FT in the front-rear direction, the position in the up-down direction, and the rotation angle α are controlled such that the rear end RP of the shoulder in the scanning direction moves along the broken line La. That is, the depth of entry d is maintained at an optimum value d₀. Therefore, the occurrence of the bonding defect can be suppressed. In the present embodiment, only the position of the friction stir tool FT in the front-rear direction, the position in the up-down direction, and the rotation angle α are controlled. That is, for example, unlike the first embodiment, the advance angle θ is not controlled. Therefore, the computer program for controlling the friction stir tool FT and the configurations of the various actuators can be simplified.

(third embodiment)

Next, a procedure for manufacturing a product similar to that of the first embodiment by using the friction stir welding method according to the third embodiment of the present invention will be described.

(Butt-joining step)

In the present embodiment, the first member 10 and the second member 20 are also butted against each other, as in the first embodiment. Since the specific procedure of the docking process is the same as that of the first embodiment, the description thereof will be omitted.

(joining Process)

As in the first embodiment, the first to fifth portions to be friction stir welded WP1 to WP5 are continuously welded in this order. A series of steps from the joining of the first friction stir welding target portion WP1 to the joining of the third friction stir welding target portion WP3 is substantially the same as a series of steps from the joining of the third friction stir welding target portion WP3 to the joining of the fifth friction stir welding target portion WP5. A series of steps from the joining of the first friction stir welding target portion WP1 to the joining of the third friction stir welding target portion WP3 will be described below, and a series of steps from the joining of the third friction stir welding target portion WP3 to the joining of the fifth friction stir welding target portion WP5 will be omitted from the description.

First, the position and posture of the friction stir tool FT with respect to the first members 10 and 2 members 20 are set in the same manner as in the start of the joining according to the first embodiment.

Next, as in the first embodiment, the friction stir tool FT descends while rotating about the center axis CA, and the tip end portion of the friction stir tool FT is pushed into the rear end portion of the first friction stir welding target site WP1 (see fig. 3). The advance angle θ is set to 3 °, for example. Thus, the depth of entry d is set to an optimum value d₀(e.g., 0.3 mm).

Next, the friction stir tool FT scans forward (rightward in fig. 3) (parallel movement). Among the parameters relating to the position and orientation of the friction stir tool FT, parameters other than the parameter relating to the position in the front-rear direction are not changed. Thereby, the rear end RP of the shoulder in the scanning direction moves along the broken line La in fig. 3. That is, the depth of entry d is maintained at an optimum value d₀. Further, the tip DP of the probe portion PR moves along the broken line Lb. That is, the stirring depth D is maintained at the optimum value D₀. As shown in fig. 4, when the tip DP of the probe portion PR of the friction stir tool FT reaches the boundary BD between the first friction stir welding target portion WP1 and the second friction stir welding target portion WP2₁₂At this time, the forward scanning of the friction stir tool FT is stopped.

Next, the friction stir tool FT starts scanning (rotating) around the center axis O of the outer peripheral surface S2 of the second friction stir welding target portion WP2. At this time, various parameters regarding the position and the posture of the friction stir tool FT are changed so that the rear end RP of the shoulder portion of the friction stir tool FT in the scanning direction moves along the broken line La in fig. 18. That is, various parameters are changed so that the depth d of penetration of the shoulder of the friction stir tool FT is maintained at the optimum value d₀(e.g., 0.3 mm).

If, as shown in fig. 16, the rotation angle α of the friction stir tool FT about the central axis O starts to increase, and if, of the parameters relating to the position and orientation of the friction stir tool FT, the parameters other than the rotation angle α are not changed,the rear end RP of the shoulder in the scanning direction is deviated from the broken line La in fig. 16. That is, the entry depth d becomes gradually smaller. As shown in fig. 17, the friction stir tool FT is gradually moved in the extending direction of the center axis CA, and the amount of the friction stir tool FT pushed into the friction stir welding target portion WP is gradually increased such that the rotation angle α of the friction stir tool FT is gradually increased and the depth d of penetration is maintained at the optimum value d₀. Thereby, the tip DP of the probe portion PR is slightly deviated from the broken line Lb in fig. 17. I.e. the mixing depth D is less than the optimum value D₀Becoming slightly deeper. When the rear end RP of the shoulder in the scanning direction reaches the boundary BD₁₂In this case (see fig. 18), the movement of the friction stir tool FT in the extending direction of the central axis CA (change of the pushing amount) is stopped.

Subsequently, the friction stir tool FT further rotates around the center axis O. In addition, among the parameters regarding the position and the posture of the friction stir tool FT, the parameters other than the rotation angle α are not changed. That is, the push-in amount at the time shown in fig. 17 is maintained. Thereby, the rear end RP of the shoulder in the scanning direction moves along the broken line La in fig. 18. That is, the depth of entry d is maintained at an optimum value d₀. On the other hand, the tip DP of the probe portion PR is slightly deviated from the broken line Lb in fig. 18. I.e. the mixing depth D is less than the optimum value D₀Slightly deeper. When the rotation angle α reaches "90 °" (i.e., the tip DP of the probe portion PR reaches the boundary portion BD)₂₃At that time), the rotation of the friction stir tool FT about the center axis O is stopped.

Subsequently, the friction stir tool FT starts scanning downward (parallel movement). It is assumed that, when the friction stir tool FT starts scanning downward as shown in fig. 19, the depth of penetration d gradually increases when, of the parameters relating to the position and the posture of the friction stir tool FT, the parameters other than the parameters relating to the position in the vertical direction are not changed. As shown in fig. 20, the friction stir tool FT is moved in the extending direction of the center axis CA, and the pushing amount is gradually reduced so that the friction stir tool FT is moved in parallel downward and the depth d of penetration is maintained at the optimum value d₀. In fig. 20, the tip DP of the probe portion PR is shifted slightly from the broken line Lb. I.e. the mixing depth D is at its maximumGood value D₀Slightly deeper. When the rear end RP of the shoulder in the scanning direction reaches the boundary BD₂₃In this case (see fig. 21), the tip DP of the probe portion PR intersects the broken line Lb in fig. 20. At this time, the movement of the friction stir tool FT in the extending arrangement direction of the center axis CA (change of the pushing amount) is stopped.

Subsequently, the friction stir tool FT is further scanned downward (moved in parallel). Among the parameters relating to the position and orientation of the friction stir tool FT, parameters other than the parameters relating to the position in the vertical direction are not changed. Thereby, the rear end RP of the shoulder in the scanning direction moves along the broken line La in fig. 21. That is, the depth of entry d is maintained at an optimum value d₀. Further, the tip DP of the probe portion PR moves along a broken line Lb in fig. 21. That is, the stirring depth D is maintained at the optimum value D₀. As described above, the first to third portions to be friction stir welded WP1 to WP3 are welded.

As described above, in the present embodiment, the position of the friction stir tool FT in the front-rear direction, the position in the up-down direction, the rotation angle α, and the pushing-in amount are controlled such that the rear end RP of the shoulder in the scanning direction moves along the broken line La. That is, the entry depth d is maintained at the optimum value d 0. Therefore, the occurrence of the bonding defect can be suppressed. In the present embodiment, the amount of insertion of the friction stir tool FT at the bent portion (the second friction stir welding target portion WP2 and the fourth friction stir welding target portion WP4) is slightly larger than that at the straight portion (the first friction stir welding target portion WP1, the third friction stir welding target portion WP3, and the fifth friction stir welding target portion WP 5). That is, the stirring depth D of the curved portion (i.e., the depth of the portion to be joined) is slightly larger than the stirring depth D of the linear portion. Therefore, the joining strength of the curved portion can be set higher than the joining strength of the linear portion. The rear half of the shoulder portion enters the friction stir welding target portion in the scanning direction and moves along a first line La that enters the outer peripheral surface by a predetermined distance. Further, the distal end DP of the probe portion of the friction stir tool moves along the second line Lb that enters from the outer peripheral surface by a predetermined distance, and thus the bonding strength of the bent portion can be uniformly set higher.

In addition, the present invention is not limited to the above embodiments, and various modifications may be made without departing from the object of the present invention.

In the above embodiment, the first member 10 and the second member 20 are fixed in advance, and the friction stir tool FT is moved relative to the first member 10 and the second member 20. Alternatively, the friction stir tool FT may be fixed in advance and the first member 10 and the second member 20 may be moved relative to the friction stir tool FT in such a manner that the relative positions and postures of the first member 10 and the second member 20 and the friction stir tool FT are the same as those of the above-described embodiment. The friction stir tool FT may be moved and the first member 10 and the second member 20 may be moved relative to the friction stir tool FT in such a manner that the relative position and posture to the friction stir tool FT are the same as those in the above-described embodiment.

Description of the reference numerals

A first component; a second component; a sidewall portion; 12.. peripheral wall portion BD₁₂.., interface; BD₂₃.., interface; CA.. a central axis; DP... top end; DR.. a drive arrangement; FT.. a friction stir tool; n.. normal; o. a central axis; PR.. a probe portion; RP.. a rear end; s1, S2, S3.. peripheral surface; WP.. friction stir welding target part; a first friction stir welding target site; a second friction stir welding target site; a third friction stir welding target site; a fourth friction stir welding target site; a fifth friction stir welding target site; rotating an angle; a forward angle.

Claims

1. A friction stir welding method characterized by continuously welding a first friction stir welding target site and a second friction stir welding target site formed by sites located on both sides of a butt joint surface of 2 members in this order by scanning a friction stir tool along the first friction stir welding target site having a planar outer peripheral surface extending in a predetermined direction and the second friction stir welding target site having a curved outer peripheral surface extending in the predetermined direction from an end of the outer peripheral surface of the first friction stir welding target site in the extending direction,

controlling relative positions or postures of the friction stir welding tool and the 2 members so that a rear half portion of a shoulder portion of the friction stir welding tool in the scanning direction enters deeper into the friction stir welding target portion than a front half portion, and an entering depth of the shoulder portion into the first friction stir welding target portion is the same as an entering depth of the shoulder portion into the second friction stir welding target portion.

2. The friction stir welding method according to claim 1,

setting an advancing angle of the friction stir tool at the first friction stir welding target site to a prescribed value,

when the tip end portion of the friction stir welding tool reaches the boundary portion between the first friction stir welding target site and the second friction stir welding target site, the friction stir welding tool is started to rotate about the central axis of the outer peripheral surface of the second friction stir welding target site, and the advance angle is gradually changed.

3. The friction stir welding method according to claim 1,

when a portion of the shoulder portion on a rear end side in the scanning direction reaches a boundary portion between the first friction stir welding target portion and the second friction stir welding target portion, the friction stir tool is started to rotate around a central axis of an outer peripheral surface of the second friction stir welding target portion.

4. The friction stir welding method according to claim 1, wherein an advancing angle of the friction stir tool at the first friction stir welding target site is set to a prescribed value,

when the tip end portion of the friction stir welding tool reaches the boundary portion between the first friction stir welding target site and the second friction stir welding target site, the friction stir welding tool starts rotating around the central axis of the outer peripheral surface of the second friction stir welding target site and gradually changes the stirring depth of the friction stir welding tool.

5. The friction stir welding method according to claim 1 or 2,

the rear half of the shoulder portion enters the friction stir welding target portion in the scanning direction and moves along a first line (La) that enters a predetermined distance from the outer peripheral surface.

6. The friction stir welding method according to claim 5,

a tip (DP) of a probe portion of the friction stir tool moves along a second line (Lb) that enters a predetermined distance from the outer peripheral surface.